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