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