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