One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,7)(5,8)(9,10)(11,18)(12,21)(13,16)(14,20)(15,17)(19,23)(22,24)(25,26,30,33)(27,29,32,35)(28,31,38,40)(34,37,36,39)(1,3)(2,5)(4,8)(6,7)(9,11)(10,14)(12,22)(13,19)(15,20)(16,24)(17,18)(21,23)(25,27)(26,29)(28,36)(30,32)(31,39)(33,35)(34,38)(37,40) involution — undirected(9,12,15,13)(10,16,17,21)(11,19,20,22)(14,23,18,24)(25,28)(26,31)(27,34)(29,37)(30,38)(32,36)(33,40)(35,39)(1,2)(3,6)(4,7)(5,8)(9,11)(10,14)(12,19)(13,22)(15,20)(16,23)(17,18)(21,24)(25,26)(27,35)(28,31)(29,32)(30,33)(34,39)(36,37)(38,40) involution — undirected(1,2)(3,5)(4,7)(6,8)(9,13,15,12)(10,16,17,21)(11,19,20,22)(14,24,18,23)(25,28)(26,31)(27,36)(29,39)(30,38)(32,34)(33,40)(35,37)(1,3)(2,6)(4,8)(5,7)(9,14)(10,11)(12,23)(13,24)(15,18)(16,19)(17,20)(21,22)(25,29,30,35)(26,32,33,27)(28,37,38,39)(31,36,40,34)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.