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)(11,12)(13,17)(14,16)(15,19)(18,20)(21,23)(22,24)(25,26,30,34)(27,35,36,31)(28,32,38,39)(29,33,40,37)(1,2)(3,6)(4,7)(5,8)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,23)(21,24)(25,27)(26,31)(28,37)(29,39)(30,36)(32,40)(33,38)(34,35) involution — undirected(1,3,5,4)(2,6,8,7)(10,16)(12,15)(17,23)(20,22)(27,36)(28,38)(31,35)(32,39)(9,12,14,15)(10,11,16,19)(13,20,21,22)(17,18,23,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,36)(37,40)(38,39)(1,3,5,4)(2,6,8,7)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,23)(21,24)(25,28,30,38)(26,32,34,39)(27,37,36,33)(29,31,40,35)(1,4,5,3)(2,7,8,6)(9,13,14,21)(10,17,16,23)(11,18,19,24)(12,20,15,22)(25,29,30,40)(26,33,34,37)(27,32,36,39)(28,35,38,31)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.