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