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