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