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