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