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