One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,15,20)(11,21,23,16)(12,14,19,17)(13,24,22,18)(25,26,30,34)(27,35,36,31)(28,32,37,40)(29,33,38,39)(1,2)(3,6)(4,7)(5,8)(9,11)(10,16)(12,13)(14,18)(15,23)(17,24)(19,22)(20,21)(27,36)(28,37)(31,35)(32,40) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,12,15,19)(10,17,20,14)(11,13,23,22)(16,24,21,18)(25,27,30,36)(26,31,34,35)(28,38,37,29)(32,33,40,39)(3,8)(5,6)(9,12)(10,17)(11,22)(13,23)(14,20)(15,19)(16,18)(21,24)(25,28,30,37)(26,32,34,40)(27,29,36,38)(31,39,35,33)(1,2)(3,5)(4,7)(6,8)(9,13,15,22)(10,18,20,24)(11,12,23,19)(14,21,17,16)(25,26)(27,31)(28,32)(29,39)(30,34)(33,38)(35,36)(37,40)(1,3)(2,6)(4,8)(5,7)(9,14,15,17)(10,19,20,12)(11,18,23,24)(13,16,22,21)(25,29)(26,33)(27,28)(30,38)(31,40)(32,35)(34,39)(36,37)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.