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