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