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