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