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