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