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