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