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